add custom derive for interbtc native balances (#6779)

Signed-off-by: Gregory Hill <gregorydhill@outlook.com>

packages/apps-config/src/api/spec/interbtc.ts

@@ -1,12 +1,67 @@
 // Copyright 2017-2022 @polkadot/apps-config authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
+/* eslint-disable @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-assignment */
+
+import type { Observable } from 'rxjs';
+import type { ApiInterfaceRx } from '@polkadot/api/types';
 import type { OverrideBundleDefinition } from '@polkadot/types/types';
 
-import definitions from '@interlay/interbtc-types';
+import interbtc from '@interlay/interbtc-types';
+import { combineLatest, map } from 'rxjs';
 
-// This is a temp work-around to add the interfaces key to the actual types
-// With the next release of the API this should be able tp be added to the base
-const extended = definitions as OverrideBundleDefinition;
+import { DeriveBalancesAll } from '@polkadot/api-derive/types';
+import { memo } from '@polkadot/api-derive/util';
+import { TypeRegistry, U128 } from '@polkadot/types';
+import { BN, formatBalance } from '@polkadot/util';
 
-export default extended;
+function balanceOf (number: number | string): U128 {
+  return new U128(new TypeRegistry(), number);
+}
+
+function defaultAccountBalance (): DeriveBalancesAll {
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-return
+  return {
+    accountNonce: new BN(1),
+    additional: [],
+    availableBalance: balanceOf(0),
+    freeBalance: balanceOf(0),
+    lockedBalance: balanceOf(0),
+    lockedBreakdown: [],
+    reservedBalance: balanceOf(0)
+  } as any;
+}
+
+export function getBalance (
+  instanceId: string,
+  api: ApiInterfaceRx
+): () => Observable<DeriveBalancesAll> {
+  const nativeToken = api.registry.chainTokens[0] || formatBalance.getDefaults().unit;
+
+  return memo(
+    instanceId,
+    (account: string): Observable<DeriveBalancesAll> =>
+      combineLatest([api.query.tokens.accounts(account, { Token: nativeToken })]).pipe(
+        map(([data]: [any]): DeriveBalancesAll => {
+          return {
+            ...defaultAccountBalance(),
+            freeBalance: data.free,
+            lockedBalance: data.frozen,
+            reservedBalance: data.reserved
+          };
+        })
+      )
+  );
+}
+
+const definitions: OverrideBundleDefinition = {
+  derives: {
+    balances: {
+      all: getBalance
+    }
+  },
+
+  ...interbtc
+} as any;
+
+export default definitions;